React Native - What is reactTag parameter in AccessibilityInfo.setAccessibilityFocus()?

Question

What is reactTag parameter in AccessibilityInfo.setAccessibilityFocus(reactTag) method? React native documentation don't provide any information about this parameter:

Set accessibility focus to a React component. On Android, this is equivalent to UIManager.sendAccessibilityEvent(reactTag, UIManager.AccessibilityEventTypes.typeViewFocused);.

I don't have any background of Objective-C and Java. A little example will be more appreciated. Thank !!!

Answer 1

reactTag is simply a number that is used by react to identify view objects in your application. It is the result of findNodeHandle function, which takes a view reference as parameter.

Here's a simple example on how you can use it:

import React, {Component} from 'react'
import {
  ...
  findNodeHandle,
  ...
} from 'react-native';

class Sample extends React.Component {
    constructor(props) {
        super(props)
        this.viewRef = null;
    }

    ...

    componentDidMount() {
        if (this.viewRef) {
            const reactTag = findNodeHandle(this.viewRef);
            AccessibilityInfo.setAccessibilityFocus(reactTag);
        }
    }

    render() {
        return (
            <View ref={el => { this.viewRef = el }}>
                ...
            </View>
        )
    }
}